feat: improve opening trainer flow and add deviation dialog

- Add tutor message guardrail to prevent rapid-fire messages
  - Track last message by move index
  - Wait for both player and opponent moves before speaking
  - Speak immediately when player deviates from theory

- Add deviation dialog with three options:
  - Continue Playing (Start Game) - transitions to game mode
  - Undo & Return to Opening - returns to theory
  - Explore This Variation - continues off-book practice

- Implement smooth game mode transition:
  - Pass opening context from trainer to game
  - Tutor welcomes player with context about their study
  - Computer makes first move if needed in starting position

- Fix generate-test-fixtures script:
  - Add safety check to prevent overwriting real data
  - Restore full opening database (12,379 openings)
  - Rebuild move index (12,377 sequences)
  - Add clear warnings about test fixtures

- Update ChessGame to accept openingContext prop
- Update Tutor to display contextual greeting in game mode

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

e2e/global-setup.ts

@@ -0,0 +1,35 @@
+import fs from 'fs';
+import path from 'path';
+
+/**
+ * Global setup for Playwright e2e tests
+ * Copies test fixtures to public directory before tests run
+ */
+export default function globalSetup() {
+  console.log('🔧 Setting up e2e test environment...');
+
+  const fixturesDir = path.join(__dirname, 'fixtures/openings');
+  const targetDir = path.join(__dirname, '../public/openings');
+
+  // Ensure target directory exists
+  if (!fs.existsSync(targetDir)) {
+    fs.mkdirSync(targetDir, { recursive: true });
+  }
+
+  // Copy fixture files
+  const files = ['ecoA.json', 'ecoB.json', 'ecoC.json', 'ecoD.json', 'ecoE.json', 'moveIndex.json'];
+
+  for (const file of files) {
+    const source = path.join(fixturesDir, file);
+    const target = path.join(targetDir, file);
+
+    if (fs.existsSync(source)) {
+      fs.copyFileSync(source, target);
+      console.log(`   ✓ Copied ${file}`);
+    } else {
+      console.warn(`   ⚠️  Fixture not found: ${file}`);
+    }
+  }
+
+  console.log('✅ Test fixtures ready\n');
+}